Lecithins, acetylated

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Lecithins, acetylated

EC Number:

293-316-5

EC Name:

Lecithins, acetylated

Cas Number:

91053-50-8

Molecular formula:

Not applicable- complex UVCB substance

IUPAC Name:

91053-50-8

Details on test material:

Purity: Unknown variable composition biological substance (UVCBS)
Composition of test material, percentage of components: Unknown variable composition biological substance (UVCBS)

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/JHsd

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 9 weeks
- Weight at study initiation: 22.0-23.0 grams
- Housing: in stainless steel, wire-mesh cages suspended above cage boards. During quarantine, animals were housed singly or in pairs. After assignment to groups, and during the dosing and resting phases of the study, animals were housed singly.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light):12-hour light/dark cycle

Study design: in vivo (LLNA)

Vehicle:

methyl ethyl ketone

Concentration:

0 (Vehicle Control), 10, 25, 50, 100%
25% (Positive control)

No. of animals per dose:

5 females mice

Details on study design:

Twenty-five μL of vehicle control, the test substance, or positive control were administered topically to the dorsum of each mouse ear for 3 consecutive days (test days 0-2). Test days 3-4 were days of rest followed by intravenous injection of 20 μCi of ³H-thymidine in PBS per mouse on test day 5.
Approximately 5 hours after the injection, animals were sacrificed by carbon dioxide asphyxiation, draining auricular lymph nodes were removed, and single cell suspensions were prepared. The single cell suspensions were incubated at 2-8°C overnight. On test day 6, the single cell suspensions were counted on a beta counter and reported as disintegrations per minute (dpm).

Study Parameters and Frequency
Body Weight: Test days 0 and 5
Daily Animal Health Observations: At least once daily
Careful Clinical Observations: Prior to dosing and prior to sacrifice
Dosing: Test days 0-2
Days of Rest: Test days 3-4
Injection of Radioactivity: Test day 5
Removal of Lymph Nodes: At sacrifice (test day 5)
Disintegrations per minute (dpm) data: Test day 6

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

See Table 1

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.65

Test group / Remarks:

10%

Remarks on result:

other: 10% test group

Results 2

Parameter:

SI

Value:

1.66

Test group / Remarks:

25%

Remarks on result:

other: 25% test group

Results 3

Parameter:

SI

Value:

3.35

Test group / Remarks:

50%

Remarks on result:

other: 50% test group

Results 4

Parameter:

SI

Value:

10.33

Test group / Remarks:

100%

Remarks on result:

other: 100% test group

Any other information on results incl. tables

Table 2: Stimulation Index Data

Group	Material Tested	Mean (dpm)	S.D. (dpm)	SI
1	0% Vehicle Control	535.55	310.20	N/A
2	10%	885.15	287.71	1.65
3	25%	889.35	232.56	1.66
4	50%	1792.95#	297.64	3.35
5	100%	5529.75#	1527.74	10.33
6	25% Positive Control	5274.95	1457.94	9.85
# Statistically significant increase in dpm data from vehicle control at p < 0.01 by Jonckheere-Terpstra trend test.

 

Applicant's summary and conclusion

Interpretation of results:

other: Produced sensitising effects

Conclusions:

Based on these data, and according to the guidance provided by the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC), the test substance produced effects that could indicate it is a dermal sensitiser. However, the weight-of-evidence evaluation discussed in the endpoint summary supports that it should not be classified for dermal sensitisation.

Executive summary:

The objective of this study was to evaluate the potential of the test substance to produce a dermal sensitisation response in mice using the local lymph node assay (LLNA). Five groups of 5 female CBA/JHsd mice were dosed for 3 consecutive days with 0% (vehicle control), 10%, 25%, 50%, or 100% of the test substance on both ears. Methyl ethyl ketone (MEK) was used as the diluting vehicle. One group of 5 female mice was dosed for 3 consecutive days with 25% hexylcinnamaldehyde (HCA) in MEK as a positive control. On test day 5 of the assay, mice received ³H-thymidine by tail vein injection and were sacrificed approximately 5 hours later. The cell proliferation in the draining auricular lymph nodes of the ears from the test substance groups was then evaluated and compared to the vehicle control group. No statistically significant differences in mean body weights and body weight gains compared to the vehicle control group were observed at any test concentration. Hair loss on the neck was observed on test day 5 in one mouse treated at the 10% concentration and in all 5 mice treated at the 100% concentration of test substance. Statistically significant increases in cell proliferation measurements compared to the vehicle control group were observed at the 50% and 100% test concentrations. Stimulation indices (SIs) of greater than 3.0 were observed at the 50% and 100% test concentrations of the test substance. The EC3 value (the estimated concentration required to induce a threshold positive response, i.e., SI = 3) for the test substance under the conditions of this study was calculated to be 45%. A 25% concentration of the positive control, HCA, produced a dermal sensitisation response in mice. Therefore, the LLNA test system was valid for this study. Under the conditions of this study, the test substance produced effects that could indicate it is a dermal sensitizer in mice according to the guidance provided by the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC). However, the weight-of-evidence evaluation discussed in the endpoint summary supports that it should not be classified for dermal sensitisation.